Re: [PATCH v2 2/2] Revert "usb: dwc3: Don't switch OTG -> peripheral if extcon is present"

[Ferry Toth]

On 07-10-2022 04:11, Thinh Nguyen wrote:
> On Thu, Oct 06, 2022, Ferry Toth wrote:
> > Hi
> >
> > On 06-10-2022 04:12, Thinh Nguyen wrote:
> > > On Wed, Oct 05, 2022, Ferry Toth wrote:
> > > > Hi,
> > > >
> > > >       Thanks!
> > > >
> > > >       Does the failure only happen the first time host is initialized? Or can
> > > >       it recover after switching to device then back to host mode?
> > > >
> > > > I can switch back and forth and device mode works each time, host mode remains
> > > > dead.
> > > Ok.
> > >
> > > >       Probably the failure happens if some step(s) in dwc3_core_init() hasn't
> > > >       completed.
> > > >
> > > >       tusb1210 is a phy driver right? The issue is probably because we didn't
> > > >       initialize the phy yet. So, I suspect placing dwc3_get_extcon() after
> > > >       initializing the phy will probably solve the dependency problem.
> > > >
> > > >       You can try something for yourself or I can provide something to test
> > > >       later if you don't mind (maybe next week if it's ok).
> > > >
> > > > Yes, the code move I mentioned above "moves dwc3_get_extcon() until after
> > > > dwc3_core_init() but just before dwc3_core_init_mode(). AFAIU initially
> > > > dwc3_get_extcon() was called from within dwc3_core_init_mode() but only for
> > > > case USB_DR_MODE_OTG. So with this change order of events is more or less
> > > > unchanged" solves the issue.
> > > I saw the experiment you did from the link you provided. We want to also
> > > confirm exactly which step in dwc3_core_init() was needed.
> > Ok. I first tried the code move suggested by Andrey (didn't work). Then
> > after reading the actual code I moved a bit further.
> >
> > This move was on top of -rc6 without any reverts. I did not make additional
> > changes to dwc3_core_init()
> >
> > So current v6.0 has: dwc3_get_extcon - dwc3_get_dr_mode - ... -
> > dwc3_core_init - .. - dwc3_core_init_mode (not working)
> >
> > I changed to: dwc3_get_dr_mode - dwc3_get_extcon - .. - dwc3_core_init - ..
> > - dwc3_core_init_mode (no change)
> >
> > Then to: dwc3_get_dr_mode - .. - dwc3_core_init - .. - dwc3_get_extcon -
> > dwc3_core_init_mode (works)
> >
> > .. are what I believe for this issue irrelevant calls to
> > dwc3_alloc_scratch_buffers, dwc3_check_params and dwc3_debugfs_init.
> Right. Thanks for narrowing it down. There are still many steps in
> dwc3_core_init(). We have some suspicion, but we still haven't confirmed
> the exact cause of the failure. We can write a proper patch once we know
> the reason.
If you would like me to test your suspicion, just tell me what to do :-)
> Thanks,
> Thinh